If you’ve ever written code to intersect two featureclasses, you probably realize that there are different approaches to take. The optimal approach really depends on the featureclasses being intersected. If one of the featureclasses is small, it’s probably best to just cache it in memory as something akin to a spatial hashtable. If it is larger, maybe use IFeatureIndex or ISpatialCacheManager. Also the max number of features intersected in featureclassA by a feature in featureclassB could be taken into account, which ArcSDE should be able to answer fairly quickly.
Oracle provides a nice capability called “explain plan”. It would be nice if ArcGIS provided something similar, perhaps “explain geoplan”, that could be used to optimize the various geoprocessing overlay functions by looking at the size of the featureclasses along with the morphology (geomorphology?) of the envelopes of the features. Unlike Oracle though (as far as I can tell) I’d like an option to use a previously defined execution plan when I run an overlay.
Explain Geoplan could also be beefed up to recognize when distributed processing is practical. Suppose we have two feature classes such that the envelope of each feature only intersects a small number of other envelopes, e.g. census tracts. In this case it seems that the processing job could be distributed across cpus in a server cluster.
Imagine publishing a geoprocessing model onto a cluster server that would be able to quickly run the model by spreading the load across multiple cpus.
And maybe not just overlays, how about topology validation too? I recall Clint Brown mentioning how many hours (~50?) it took to validate a geodatabase topology composed of census geography for the entire US. Seems like this could be distributed too.
When ESRI points out that Google Earth can’t run geoprocessing tasks, will Google respond?
While there has been lots of talk about how Google Earth is shaking up the GIS arena, geographers seem to be forgetting Google’s core strength – distributed computing. If Google responds to ArcGIS 9.2 it seems likely they will leverage this strength.